GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 17 



est (Gatun) plant-bearing formations there is no observable dif- 

 ference in floral f acies, and while the plants are entirely too few for 

 positive conclusions, and while not much variation can be expected 

 in fossil floras of the Tropics unless after the lapse of long intervals 

 of time or the intervention of marked changes in physical conditions, 

 I am disposed to think that this so-called Oligocene series of forma- 

 tions does not represent any great interval of time. 



Nearly all of the fossil plants are new, the only outside occurrences 

 being the Hieronymia which is common to the Tertian of Ecuador 

 and the Palmoxylon and Taenioxylon both of which occur in the 

 Oligocene of the island of Antigua, and both have related types in 

 the Oligocene (Catahoula and Vicksburg) of our Southern States 

 In addition to the Hieronymia common to Ecuador there are several 

 other elements in the Tertiary flora of the latter region that are 

 similar to Panama forms, and it is not improbable that the coals of 

 Loja in the Ecuadorian Andes are the same age as the so-called 

 Oligocene series of Panama. Only one pre-Oligocene plant is re- 

 corded from Panama and the age (Eocene) rests on the stratigraphic 

 observations of Doctor MacDonald and paleontologic determinations 

 by C. W. Cooke. The form itself offers no intrinsic evidence of its 

 age and might well be early Oligocene but for the fact that Doctor 

 MacDonald collected the type stratigraphically below a bed con- 

 taining a varietal form of the mollusk, Venericardia planicosta. 



The chief question of interest in the correlation of these Panama 

 beds is their equivalence in terms of the European section. The 

 present flora offers no evidence on this point which must hence be 

 determined by the accompanying marine faunas. However, in view 

 of the traditional unscientific assumption that all of the fossilif erous 

 beds of the Carribbean region are Oligocene in age, it is of interest 

 to note that Douville 1 from a study of the foraminifera, pointed 

 out as early as 1898, that a considerable part of the so-called Oligo- 

 cene of the Isthmus was Aquitanian and Burdigalian in age ; that is 

 to say, lower Miocene according to the present conceptions of Euro- 

 pean geologists and palentologists. 



In my preliminary announcement 2 of the discovery of fossil plants 

 in the Canal Zone I stated that none of the plants recognized indi- 

 cated Eocene and that they were all probably Oligocene in age. 

 This statement was perhaps overemphasized in a desire to offset the 

 extreme views of certain foreign paleontologists who have held that 

 these faunas were young Miocene or even Pliocene. 



The question of the exact time in the Tertiary at which connections 

 between North and South America were replaced by marine condi- 

 tions is of the utmost importance in all studies of distribution of both 



1 Douvill<5, H. Bull. Soc. Geol. de France, ser. 3, vol. 26, pp. 587-600, 1898. 



2 Berry, E. W. Science, new ser., vol. 39, p. 357, 1914. 



